Two years ago, former Missouri Republican Senator John Danforth, who also served as George W. Bush’s ambassador the U.N., told the New York Times that he worried about his party’s swerve to the hard-right.

Specifically, he said, “If Dick Lugar, having served five terms in the U.S. Senate and being the most respected person in the Senate and the leading authority on foreign policy, is seriously challenged by anybody in the Republican Party, we have gone so far overboard that we are beyond redemption.”

That day, it seems, has come. Today, as early voting begins in Indiana’s GOP Senate primary, two mainstream conservative organizations are opening fire on Sen. Dick Lugar (R-IN) and backing his opponent, State Treasurer Richard Mourdock (R).

The Wall Street-backed Club for Growth Action is airing a 30-second TV ad and two 60-second radio ads tomorrow going after Lugar for being too willing to compromise with Democrats. “Dick Lugar might be a statesman, but he’s not a conservative,” one ad warns. “Indiana conservaties deserve better than Obama’s favorite Republican.”

Meanwhile, the National Rifle Association (NRA) is opening up on Lugar with a six-figure buy of TV, radio, and online ads, along with a direct mail campaign.

A new poll shows Lugar is still clinging to lead over Mourdock, but barely. The incumbent leads 42 percent to 35 percent, with pollster Christine Matthews warning the result should “be of significant concern.”

The fact that the man who literally wrote the book on the beneficence of Supreme Court Justice Clarence Thomas and helped foment support for Bill Clinton’s impeachment, is warning that his party has drifted too far to the right should give pause to Indiana Republican voters.